The present invention relates to toilet bar compositions comprising nonionic glycolipid surfactants, more specifically the invention relates to nonionic aldobionamides in combination with sufficient amount of polyalkylene glycol to act as a structurant without simultaneously inhibiting lather formation.
Soap is an efficient cleaning surfactant which has been used historically in toilet bar compositions. Because soap can be harsh on the skin, however, for many years it has been sought to find a milder (i.e., less harsh) surfactant which can be used together with or in place of soap in such toilet bar compositions. U.S. Pat. No. 4,695,395 to Caswell et al. for example, teaches a toilet bar composition comprising both soap and acyl fatty isethionate and which composition is substantially milder to the skin then pure soap.
Another goal of the art has been to utilize mild, non-soap surfactants which are prepared from natural, biodegradable materials such as, for example saccharides. Applicants' parent application, U.S. Ser. No. 981,739, for example, teaches the use of aldobionamides as surfactants, for example, in toilet bar compositions.
In non-soap detergent active bars, it is the free fatty acid which acts to structure the bar (i.e., keep it from physically falling apart). Thus, in a bar based entirely on aldobionamide active, for example, a certain minimum level of fatty acid (i.e., 5-30% by weight, preferably 15 to 25% by weight) is generally required to structure the bar.
While aldobionamide is a mild biodegradable surfactant, it has been found that the bar does not have good lather characteristics, at least when used with a fatty acid structurant. Since lather production is an important characteristic to many bar users, this is considered to be a strong negative.
U.S. Pat. No. 3,312,627 to Hooker discloses bar compositions containing 0 to 70% of a high molecular weight base component and 10% to 70% of a nonionic detergent surfactant. It is disclosed that the base polymer may be a polyglycol and that the nonionic may be stearoyl N-methyl glucamide (column 5, line 1)
It should be noted that the nonionic surfactant is a glucamide in contrast to the gluconamide of the invention. Glucamides are expected to be less soluble. This particular compound would be expected to be even less soluble in that it is a C.sub.18 stearoyl compound. In addition there is absolutely no recognition that this particular combination of components should be used or that they would result in a bar having the characteristics of the bar of the invention.
Unexpectedly, applicants have now discovered that if a certain minimum level of polyalkylene glycol is used in the composition (i.e., a minimum level of about 15% by weight alkylene glycol), the polyalkylene glycol not only can be used to structure the non-soap surfactant bar in place of fatty acid, but the polyalkylene glycol also does not inhibit lather formation in an aldonamide bar.
While U.S. Ser. No. 981,739 identified above discloses that polyethylene glycol may be used as an optional ingredient in combination with aldobionamide (page 12, second paragraph), there is no teaching or suggestion that the polyethylene glycol should or could be used in structuring amounts (i.e., in amounts greater than the amount of free fatty acid used) or that the polyethylene glycol surprisingly does not inhibit lather production in an aldobionamide bar the way free fatty acid does. In fact when alkylene glycol is used, lather volumes rivaling those of a commercial anionic bar are obtained ant lather volumes are far in excess of those obtained in a lactobionamide/fatty acid bar.